"Russia understands that the international community holds one view about the actions that Russia has taken and supported in Ukraine and that we stand prepared together with our partners to impose further costs on Russia if Russia does not take action to help stabilize the situation in Ukraine and to cease promoting destabilizing activity," White House Press Secretary Jay Carney said on Monday.

The US said if it didn't see steps being taken by Russia in the coming days to abide by its ‘commitments’ to use the influence to disarm militants and turn back over the buildings they have seized, they "are prepared to impose further costs".

Carney said the US continues to monitor events in eastern Ukraine closely.

"We've seen differing reports about what happened in Slovyansk on Monday but cannot independently confirm responsibility for these actions," he said.

The secretary said the US was concerned about the Ukraine situation and urge paramilitary groups throughout the eastern and southern parts of Ukraine to lay down their weapons and depart the buildings they have occupied as was called for in the accord signed in Geneva last week.

"We continue to call on Russia to use its influence over these groups to press them to disarm and to turn occupied buildings over to the authorities," he said.

He said the US admired the government of Ukraine for continuing to demonstrate restraint, and are hopeful that all parties in the Rada will shortly be able to agree on an amnesty bill to help deescalate the situation in the east.

"As we have said, if there is not progress within days we remain prepared, along with our European and G7 partners to impose additional costs on Russia for its destabilizing actions," he said.

"When it comes to that specific incident we are still unable independently to confirm who is responsible for what happened there but there is no question that there has been a great deal of destabilizing activity and that Russia has influence over the groups that have engaged in that activity, who have seized buildings," he added.

Carney said the US continued to observe the volatile and tense situation in eastern Ukraine that requires steps be taken to stabilize.

"We have been very clear that we firmly believe that Russia has supported the so-called separatists in eastern Ukraine that have popped up with arms to seize buildings, to stockpile weapons, to erect roadblocks. And Russia needs to abide by the agreement signed in Geneva and to take steps to help stabilize the situation," he asserted.